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The glycoprotein Ib-IX-V complex is a platelet counterreceptor for P-selectin.

Romo GM, Dong JF, Schade AJ, Gardiner EE, Kansas GS, Li CQ, McIntire LV, Berndt MC, López JA - J. Exp. Med. (1999)

Bottom Line: Cells expressing P-selectin adhered to immobilized GP Ibalpha, and GP Ibalpha-expressing cells adhered to and rolled on P-selectin and on histamine-stimulated endothelium in a P-selectin-dependent manner.Unlike the P-selectin interaction with its leukocyte ligand, PSGL-1 (P-selectin glycoprotein ligand 1), the interaction with GP Ibalpha required neither calcium nor carbohydrate core-2 branching or alpha(1,3)-fucosylation.The interaction was inhibited by sulfated proteoglycans and by antibodies against GP Ibalpha, including one directed at a tyrosine-sulfated region of the polypeptide.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Baylor College of Medicine and Veterans Affairs Medical Center, Houston, Texas 77030, USA.

ABSTRACT
We have identified platelet glycoprotein (GP) Ibalpha as a counterreceptor for P-selectin. GP Ibalpha is a component of the GP Ib-IX-V complex, which mediates platelet adhesion to subendothelium at sites of injury. Cells expressing P-selectin adhered to immobilized GP Ibalpha, and GP Ibalpha-expressing cells adhered to and rolled on P-selectin and on histamine-stimulated endothelium in a P-selectin-dependent manner. In like manner, platelets rolled on activated endothelium, a phenomenon inhibited by antibodies to both P-selectin and GP Ibalpha. Unlike the P-selectin interaction with its leukocyte ligand, PSGL-1 (P-selectin glycoprotein ligand 1), the interaction with GP Ibalpha required neither calcium nor carbohydrate core-2 branching or alpha(1,3)-fucosylation. The interaction was inhibited by sulfated proteoglycans and by antibodies against GP Ibalpha, including one directed at a tyrosine-sulfated region of the polypeptide. Thus, the GP Ib-IX-V complex mediates platelet attachment to both subendothelium and activated endothelium.

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Rolling of GP Ibα–expressing cells on immobilized P-selectin. (A) CHO cells expressing either the GP Ib-IX complex or only GP Ibβ and GP IX were allowed to settle onto coverslips coated with P-selectin in parallel plate flow chambers. After 1 min, the chambers were perfused with PBS at a constant flow rate to generate a shear stress of 2 dynes/cm2. The top panels show cells before application of shear stress, and the bottom panels show the same region during perfusion. The images in the bottom panels represent a compilation of a series of frames taken over 2 s. The linear blurs represent those cells that have adhered to the matrix and are rolling on it. (B) Velocity and numbers of cells rolling on immobilized P-selectin. Both L and CHO cells were studied, with no significant differences noted between the two in either velocity or number of rolling cells. The presence of GP V also did not influence rolling. No velocity is given for cells lacking GP Ibα because no rolling cells were observed. The number of cells rolling per field were counted during a 3-min interval from the start of the perfusion.
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Figure 4: Rolling of GP Ibα–expressing cells on immobilized P-selectin. (A) CHO cells expressing either the GP Ib-IX complex or only GP Ibβ and GP IX were allowed to settle onto coverslips coated with P-selectin in parallel plate flow chambers. After 1 min, the chambers were perfused with PBS at a constant flow rate to generate a shear stress of 2 dynes/cm2. The top panels show cells before application of shear stress, and the bottom panels show the same region during perfusion. The images in the bottom panels represent a compilation of a series of frames taken over 2 s. The linear blurs represent those cells that have adhered to the matrix and are rolling on it. (B) Velocity and numbers of cells rolling on immobilized P-selectin. Both L and CHO cells were studied, with no significant differences noted between the two in either velocity or number of rolling cells. The presence of GP V also did not influence rolling. No velocity is given for cells lacking GP Ibα because no rolling cells were observed. The number of cells rolling per field were counted during a 3-min interval from the start of the perfusion.

Mentions: The P-selectin–mediated rolling of platelets on inflamed endothelium requires rapid on and off rates. Thus, for the GP Ib-IX-V complex to constitute a physiological counterreceptor for P-selectin, it should be able to support a similar rolling interaction. To test this possibility, we perfused cells expressing full or partial complexes over coverslips coated with P-selectin in a parallel plate flow chamber at a shear stress of 2 dynes/cm2. Cells were observed to adhere to and roll on P-selectin (Fig. 4 A). The rolling interaction was independent of cell type, as both CHO and L cells expressing the complex rolled at similar velocities, whereas control cells lacking GP Ibα did not adhere or roll (Fig. 4 B).


The glycoprotein Ib-IX-V complex is a platelet counterreceptor for P-selectin.

Romo GM, Dong JF, Schade AJ, Gardiner EE, Kansas GS, Li CQ, McIntire LV, Berndt MC, López JA - J. Exp. Med. (1999)

Rolling of GP Ibα–expressing cells on immobilized P-selectin. (A) CHO cells expressing either the GP Ib-IX complex or only GP Ibβ and GP IX were allowed to settle onto coverslips coated with P-selectin in parallel plate flow chambers. After 1 min, the chambers were perfused with PBS at a constant flow rate to generate a shear stress of 2 dynes/cm2. The top panels show cells before application of shear stress, and the bottom panels show the same region during perfusion. The images in the bottom panels represent a compilation of a series of frames taken over 2 s. The linear blurs represent those cells that have adhered to the matrix and are rolling on it. (B) Velocity and numbers of cells rolling on immobilized P-selectin. Both L and CHO cells were studied, with no significant differences noted between the two in either velocity or number of rolling cells. The presence of GP V also did not influence rolling. No velocity is given for cells lacking GP Ibα because no rolling cells were observed. The number of cells rolling per field were counted during a 3-min interval from the start of the perfusion.
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Related In: Results  -  Collection

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Figure 4: Rolling of GP Ibα–expressing cells on immobilized P-selectin. (A) CHO cells expressing either the GP Ib-IX complex or only GP Ibβ and GP IX were allowed to settle onto coverslips coated with P-selectin in parallel plate flow chambers. After 1 min, the chambers were perfused with PBS at a constant flow rate to generate a shear stress of 2 dynes/cm2. The top panels show cells before application of shear stress, and the bottom panels show the same region during perfusion. The images in the bottom panels represent a compilation of a series of frames taken over 2 s. The linear blurs represent those cells that have adhered to the matrix and are rolling on it. (B) Velocity and numbers of cells rolling on immobilized P-selectin. Both L and CHO cells were studied, with no significant differences noted between the two in either velocity or number of rolling cells. The presence of GP V also did not influence rolling. No velocity is given for cells lacking GP Ibα because no rolling cells were observed. The number of cells rolling per field were counted during a 3-min interval from the start of the perfusion.
Mentions: The P-selectin–mediated rolling of platelets on inflamed endothelium requires rapid on and off rates. Thus, for the GP Ib-IX-V complex to constitute a physiological counterreceptor for P-selectin, it should be able to support a similar rolling interaction. To test this possibility, we perfused cells expressing full or partial complexes over coverslips coated with P-selectin in a parallel plate flow chamber at a shear stress of 2 dynes/cm2. Cells were observed to adhere to and roll on P-selectin (Fig. 4 A). The rolling interaction was independent of cell type, as both CHO and L cells expressing the complex rolled at similar velocities, whereas control cells lacking GP Ibα did not adhere or roll (Fig. 4 B).

Bottom Line: Cells expressing P-selectin adhered to immobilized GP Ibalpha, and GP Ibalpha-expressing cells adhered to and rolled on P-selectin and on histamine-stimulated endothelium in a P-selectin-dependent manner.Unlike the P-selectin interaction with its leukocyte ligand, PSGL-1 (P-selectin glycoprotein ligand 1), the interaction with GP Ibalpha required neither calcium nor carbohydrate core-2 branching or alpha(1,3)-fucosylation.The interaction was inhibited by sulfated proteoglycans and by antibodies against GP Ibalpha, including one directed at a tyrosine-sulfated region of the polypeptide.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Baylor College of Medicine and Veterans Affairs Medical Center, Houston, Texas 77030, USA.

ABSTRACT
We have identified platelet glycoprotein (GP) Ibalpha as a counterreceptor for P-selectin. GP Ibalpha is a component of the GP Ib-IX-V complex, which mediates platelet adhesion to subendothelium at sites of injury. Cells expressing P-selectin adhered to immobilized GP Ibalpha, and GP Ibalpha-expressing cells adhered to and rolled on P-selectin and on histamine-stimulated endothelium in a P-selectin-dependent manner. In like manner, platelets rolled on activated endothelium, a phenomenon inhibited by antibodies to both P-selectin and GP Ibalpha. Unlike the P-selectin interaction with its leukocyte ligand, PSGL-1 (P-selectin glycoprotein ligand 1), the interaction with GP Ibalpha required neither calcium nor carbohydrate core-2 branching or alpha(1,3)-fucosylation. The interaction was inhibited by sulfated proteoglycans and by antibodies against GP Ibalpha, including one directed at a tyrosine-sulfated region of the polypeptide. Thus, the GP Ib-IX-V complex mediates platelet attachment to both subendothelium and activated endothelium.

Show MeSH
Related in: MedlinePlus